DAWs (Digital Audio Workstations) including an audio input/output device with a PC (Personal Computer) as its operational core have been in widespread use today as music production environments. In the field of such DAWs, it has been common to add necessary hardware to the PC and execute a dedicated software application on the PC. When a rhythm pattern is to be punched or input via the DAW, for example, there is a need for a user to select by itself (i.e., himself or herself) a desired tone color, performance part (snare, high-hat cymbals, or the like), phrase etc. from a database having tone sources stored therein. Thus, if the number of the sound sources stored in the database is enormous, it would take a lot of time and labor for the user to find out or search out a desired tone source from the database. International Publication No. 2002/047066 (hereinafter referred to as “patent literature 1”) discloses a technique, which, in response to a user inputting a rhythm pattern, searches for a music piece data set corresponding to the input rhythm pattern from among music piece data sets stored in a memory and presents the thus-searched-out music piece data set. Further, Japanese Patent Application Laid-open Publication No. 2006-106818 (hereinafter referred to as “patent literature 2”) discloses a technique, in accordance with which, in response to input of a time-serial signal having an alternate repetition of ON and OFF states, a search section searches for and retrieves rhythm data having a variation pattern identical or similar to the input time-serial signal so that the thus-retrieved rhythm data set is output as a searched-out result after being imparted with related music information (e.g., name of a music piece in question).
However, if a rhythm pattern is to be directly input via an input device, such as a pad or keyboard, with the technique disclosed in patent literature 1 or patent literature 2, the rhythm pattern is input in accordance with a feeling of time passage or lapse felt by a user itself. Thus, a temporal error may occur in the input rhythm due to deviation of the user's feeling of time lapse. As a consequence, a rhythm pattern different from the rhythm pattern originally intended by the user may be output as a searched-out result (e.g., sixteenth-note phrase (hereinafter “sixteenth phrase”) different from an eighth-note phrase (hereinafter “eighth phrase”) originally intended by the user may be output as a searched-out result), which would give an uncomfortable feeling and stress to the user.